Every living first lady — including Melania Trump — has condemned the policy of separating immigrant families caught illegally crossing the U.S.-Mexico border. It is a rare moment of bipartisan unity from the women who make up the small sorority of presidential spouses.

In the past 48 hours, Laura Bush, Hillary Clinton, Michelle Obama and Rosalynn Carter all spoke out against the Trump administration’s border policy.

The issue, which is dominating national headlines, first drew a statement from the current occupant of the White House’s East Wing on Sunday afternoon, with Mrs. Trump saying to CNN that she “hates to see children separated from their families and hopes both sides of the aisle can finally come together to achieve successful immigration reform.”

Hours later, Mrs. Bush published a full-throated op-ed for The Washington Post calling camps set up to house the children taken from their parents “eerily reminiscent of the Japanese American internment camps of World War II.”

The separation policy is “immoral,” she said.

Mrs. Clinton, who often opposes President Trump, sent out a stream of tweets blasting the White House: “What’s happening to families at the border right now is a humanitarian crisis. Every parent who has ever held a child in their arms, every human being with a sense of compassion and decency, should be outraged.”

Mrs. Carter too expressed dismay over the forced separations. “When I was first lady, I worked to call attention to the plight of refugees fleeing Cambodia for Thailand,” she said Monday in a statement to The Washington Post. “I visited Thailand and witnessed firsthand the trauma of parents and children separated by circumstances beyond their control. The practice and policy today of removing children from their parents’ care at our border with Mexico is disgraceful and a shame to our country.”

Jennifer Lawless, a professor of government at American University, says there’s a lot that’s unusual about such an outcry among current and former first ladies.

It’s particularly striking, she said, to see Melania Trump take such a different tone from her husband. “I can’t come up with an example of a time that a first lady’s statement comes pretty close to contravening the West Wing,” she said. “It’s incredibly rare to have two policy statements that are pretty much at odds.”

After all, being a first lady sometimes requires some serious lip-biting, said Democratic strategist Patti Solis Doyle, who served as a White House adviser to Hillary Clinton. Mrs. Clinton privately opposed much of her husband’s welfare reform plan yet backed him, said Solis Doyle. And Michelle Obama reportedly supported same-sex marriage before her husband publicly embraced the idea.

“It is not unusual for the first lady to take on policy issues — Nancy Reagan had ‘Just say no,’ Laura Bush had literacy, Michelle Obama obesity,” Solis Doyle said. “But it’s highly unusual to use your position to go against a policy proposal your husband is putting forth.” Melania Trump’s statement, she said, “was stunning and raised eyebrows.”

Heather Higgins, the chairman of the board of the conservative Independent Women’s Forum, said she did not read Mrs. Trump’s statement as a rebuke of her husband’s policies.

“Both the President and Mrs. Trump have deeply regretted that enforcing current laws causes the separation of some children from their parents and called for both parties to effect a change to those laws,” Higgins said in an email. “There is no evidence of any difference between their positions, despite the media’s effort to manufacture a wedge and treat her as a victim without agency.”

Grisham, Mrs. Trump’s spokeswoman, did not respond to a request to elaborate on the statement.

Former first ladies, too, tend to avoid the most controversial issues, adhering to the informal practice their husbands follow of generally refraining from armchair quarterbacking.

Given the searing visuals of children being kept in cages and parents and toddlers crying, it is not surprising that the first ladies would speak out, Lawless said. Issues affecting women and children have long been the domain of a first lady’s platform.

“There’s been powerful footage and images that are resonating with people on both sides of aisle,” Lawless said. “You’re seeing both Republicans and Democrats operating with a raw sense of empathy, and a lot of people are speaking with the politics removed.”

Whether President Trump will heed the words of his wife — and her predecessors — remains in doubt. And Lawless said that could undercut Mrs. Trump’s ability to influence future policy as well as claims by her husband’s defenders that she is a moderating influence in the White House.

For her part, Mrs. Trump said in a 2016 interview that she has a mixed record when it comes to influencing her husband. “I give him my opinions, and sometimes he takes them in, and sometimes he does not.”

Emily HeilEmily Heil is the co-author of the Reliable Source and previously helped pen the In the Loop column with Al Kamen. Follow